Thermostatic control device



2 Sheets-Sheet l R. C. DEM! THERMOSTATIC CONTROL DEVICE Dec. 18, 1962Filed Dec.

Dec. 18, 1962 R. c. DEMI 3,069,039

THERMOSTATIC CONTROL DEVICE Fil ed Dec. 15, 1958 2 he ts- 2 UnitedStates Patent Ofifice 3,669,089 THERMOSTATIC CONTROL DEVICE Roy C. Demi,Greensburg, Pa., assignor toRobertshaw- Fulton Controls Company,Richmond, Va., a corporafion of Delaware Filed Dec. 15, 1958, Ser. No.780,476 6 Claims. (Cl. 236-99) This invention relates to flow controldevices and more particularly to a combined gas cock and valve forcontrolling and regulating thermostatically a flow of gaseous fuel to aburner.

An object of this invention is to facilitate the calibration ofthermostatic control device.

Another object of this invention is to lock internally the valve drivingmechanism of a thermostatic control device.

This invention has another object in that calibration of a thermostaticcontrol device may be accomplished through its control knob withoutremoving the control knob.

This invention is particularly applicable tozthe combination of a rotaryshut-oil? cock and a reciprocating disc valve which'is operableautomatically by thermally responsivemeans to maintain a predeterminedtemperature in an appliance such as the oven of a gas range. Inpracticing this invention, a :housing having an inlet and an outlet isprovided with a regulating valve assembly including :a valve memberreciprocable in response to temperature variations and a valve seatthreaded in said housing for movement to a position corresponding to ateinperaturersetting. A gas cock is seated in the housing adjacent theinlet and is internally bored tocarry a driving *element for connectionwith regulating valve member. A locking screw is received in the outerend of. the internally bored gas cock to lockthedriving element withthegas cock for unitarymovement. Calibration is effected by looseningthe locking-screw by'means of a suit-' able tool inserted through thecontrol knob ,to permit relative movement between .theggas cock andrthedriving element.

Other objects and *advantages of this invention will become apparentfrom the following description taken in connection with theaccompanyingdrawings wherein:

FIG. .-1,is a side elevation view, partly, in section, of a thermostaticvalve control embodying this invention;

-FIG.-2 iS a-SCCtiOH Of a detailstaken on line II- ll of FIG. 1 with"adjacent elements removed;

FIG. 03 is a section :View 'taken on' line -III-'IH of FIGI-Z;

l IG;--4- is'-an exploded perspective -,view .of a detail of 16. 1;

-FIGQ5 is a perspective viewaof a modified detailpand FlGQ6risanenlargedrendview of FIG. 5 inassembled relationship.

As wis :illustrated inWFIG. -1, .theathermostatic control devic eain'cludes a. housing, indicated generally at 10, having a front casing12 and a rear casing l i-secured together bysuitable. bolts 16. Theinteriorrof housing 1! ishollowed outtoform a valve chamber 13 whichestablishes communication between an inlet port,19 in the front casing12 andan outlet port 20in the rearcasing 14. iThe front casing. 121-isopenat. one end and-provided with a frusto-conical bore a forming"a-ttapered yalve seat 21 whichvintersects the inlet port-19* and.communicates ,withfthe valve .chamber .18. A generally hollow-shutoffcocklor valve member.22 has a..-correspondingz tapered surface forcooperation with, the tapered valve seat 21. i

,.A pair of: similarly constructed ports 23 ;(FIG. 2)

transversely *arranged in the. :hollow valve member 22 are connected bya relatively larger elongated :port 1 245mg per- Patented Dec. 18, 19622 mit a flow of gas from inlet 19 to an internal bore of the valve m mer 2 The o a d ert 24 's f tmqt y e Separate d in o rat on 9& ee em!reei 9 a o nt rs c the di een en e l o ea h a 3 As is illustrated inFIG. 2, only small tapering web portions 25 separate the elongated port24 from each of the rts 23. With such a construction, the gas cook 22will die liver a m m flew e t w the t we kenin t e 1 9 low part of thegas cock,

pp y pos t9 he AQL QW b e .2 th raw? eeek 22 i reduced n it o te e ipherre rm an n lar l n 28 and a l d i ee 30' ext n o g the ope g in h us n1.0-

Qu e P9. 9& of stem 30 is provided with three longitudinally extend ngslots 32 (only two being shown in 4)- radially spaced from c ether boutt e Pe i her e the v ve stem'Stl.

The valve stem 3!) is internally bored for communication with the hollowbore 26 by means of a first bore 34 and a counterbore 36 separated by anabutment shoulder 32}; A Washer 40 is mounted on the valvetstem 30 andis biased against the shoulder 28 by means of a helical coil spring 42.The coil spring 42 is mounted in compression be,- tween the washer 40and a ring-type washer 44 which is mou d on the m 30 a d is vP o de w ta Pai Qf oppositely disposed tabs 46 on its inner peripherywhich areceived in the ependinsly di ed e ete in the stem 30 for unitaryrotation of the washer 44 vand the al e mfifli 'waeh r 44 s P o dedheaethe pair of oppositely disposed perpendicularly-bent lugs 48 and 50located on its outer periphery and angularly displaced 90 from the innerperipheral tabs 46; the first lug 45 lies just inside the peripheraledge of ring washer 44 and the second lug 50 lies just outside of suchperipheral edge.

A generally cylindrical guide cover 52 is open at both n and an nul r'flan e 4., o ee dthe eq i P id t a pa eppeei e dispose moun steere 6for se uri g the s me .to th f om nde h usi .19 by suitaolefasteningrneans. An arcuate portion 5189f the a n ar flange 5. i beniperiiend eu rlyv e rebu m n y t ering u :56 t .d fine beal r t of r a oof the ring mernoer 44 and the gas cook 22. The annular flange 54 isalso provided with a pair of oppositely dis- P se rec an a pe in fil ndm.w e r pee iyely receive the lugs 48 and 50 of the ring washer 44. An inicia r fe enc m rk 63 i s r ed. enzthele ve 1am is-radially o e tequ dtantbetw en;th ra ii de n n the cover-ears 156 and extendslongitudinally along the exterior surface of the cover cylindricalportion 64. The forward end 7 of theumark, 63 .extends radially inwardlyacrossatheedge of the cylindricalportion 6,4 and thegrear: ward endextends radiallyioutwardly.across the annular flange 54 terminatingatthe edge thereof at themid-point of the rectangularopeningr62. Thecylindrical portion of-cover52 has a rectangularbent-outsection-defining an aligning tab 65' which is received inarectangular opening 66 in a split collar-68hr correctly positioning thecollar '68 on th e cover '52. W

When t l 1e cover 52 is securely fastened to the housing It, th .e iispring. 4 ,r aweehe ner ye d sev Slate held in;,asse nbledrelationshipwith the {tabs ,46 ,the inner periphery of the ringwasher- 44 extendinginwardly of the cylindrical portion 64 of cover 52. Thefsplit collar 68is mounted on the exterior of the cylindrical portion 64 of cover 52 andprovides analigning and mounting me s for e gene a ly. eas bez {71th.Afientrel re t ed m u t nar raen1 19f beze v 7 0 is pr ded it a i w d yb ai aaina tea-.1 whieh i rreee redt the p formi g th sp it e l rfifi niwith n in a d y bent biasing lug 76 frictionally retains the bezel inthe correct axial position on the collar 68.

A hollow cylindrical operating sleeve 78 rotatably extends through thecentral aperture of the bezel mounting portion 72 and slightly spacedfrom its inner end is provided with a longitudinally extending inwardlybent tang 80 intermediately spaced in angular relationship between apair of rectangular detents 82 (only one being shown). Between the endof sleeve 78 and the edge of each rectangular detent 82, the sleeve 78is indented to form a keeper 84. Adjacent its inner end, the operatingsleeve 78 is provided with calibrating indicia in the form of aplurality of longitudinally extending graduations 86 which are radiallyspaced about the outer surface of sleeve 78. The outer end of operatingsleeve 78 is provided with a longitudinally extending rectangular slot88 forming a mounting alignment for a control knob dial 90.

The control knob dial 90 is mounted on the outer end of operating sleeve78 which frictionally fits within the through bore of dial 90. Thesleeve 78 and the dial 90 are keyed for unitary rotation by means of alongitudinally extending rectangular projection 92 projecting radiallyinwardly from the wall defining the through bore and being receivedwithin the slot 88 of the sleeve 78. The outer end of dial 28 iscounterbored to define a recess 96 which frictionally receives an insertcap 98. The insert cap 98 is provided with a central aperture 99arranged on a common longitudinal axis with the operating sleeve 78 andthe gas cock 22 to form tool insertion means during a calibratingoperation.

During assembly, the dial 90 is frictionally mounted on the outer end ofoperating sleeve 78 which is inserted through the cylindrical portion 64of cover 52 and its inner end encircles the outer portion of valve stem30 in such a manner that its tang 80 is received in the intermediateslot 32 and its rectangular detents 82 are received in therespectiveslots 32. By depressing the dial 90 to its full extent, the tabs 46 onthe ring washer 44 cooperate wilh the keepers 84 to retain the dial 90and the sleeve 78 in assembled relationship with the gas cock 22.Because of the spacing of the tabs 46, the tang 80 and the detents 82which interlock with the grooves 32 in the valve siem 30, the ringwasher 44 and the operating sleeve 78 cannot be assembled incorrectly.

An operating shaft 100 extending through the gas cock 22 is slidablydisposed within the valve stem bore 34 and has an enlarged end 102disposed within valve stem bore 36 and an opposite end extending intovalve chamber 18. The enlarged head 102 has an abutting surface whichcooperates with the internal abutment shoulder 38 and such abuttingsurfaces are forced into abutting engagement by means of a set screw 104which is threaded into the threaded bore 36 whereby the operating shaft100 and the gas cock 22 are rotatable as a unit. A driving element 106in the form of a flat rectangular plate is securely keyed intermediateits edges to the inner end of the operating shaft 100 and one of suchedges 18 bent over to form an enlarged portion 108.

A portion of the internal wall defining the valve chamber 18 is providedwith threads in which an externally threaded valve seat 110 isadjustably mounted. The valve seat 110 has a generally cup-shapedconfiguration with a central aperture in its bottom wall 112 which isformed with a pair of oppositely disposed slots (not shown) havingdifferent thicknesses so that the enlarged section 108 of drive element106 can only be inserted in the larger of said slots. The mouth of thecup-shaped valve member 110 is reduced to form an angular valve seatingsurface 114.

A reciprocating disc-shaped valve member 116 is centrally apertured tobe slidably mounted on a cup-shaped hub 118 which is outwardly flangedadjacent its open end to form an annular retainer 120 for the valvemember 116. A conical helical load spring 122 has its smaller diameterportion encircling the hub 118 and is mountedin compression between theseat bottom wall 112 and the valve member 116 so that the same is alwaysbiased against the hub flange 120. A cup-shaped sleeve 124 is' slidablyreceived within the hub 118 and has its nose por-' tion abutting thebottom wall of the hub 118. The open end of cup-shaped sleeve 124 isadapted to receive the free end of a power element shaft 126 and aspring clip 128 is resiliently mounted on the exterior of sleeve 12 4*by means of a looped portion on one end while its opposite? end isprovided with a projecting tongue 130.

An ambient temperature compensator in the form of a bimetallic disc 131has a central aperture for mount-' ing on shaft 126 with its centralportion abutting the edge defining the open end of sleeve 124 and withits outer edges engaging a ring washer 133 to hold the same in abuttingrelation with a generally dish-shaped guide member 132. An annular shaftbearing 134 formed on the inner periphery of the apertured guide member132 permits a slidable mounting of the same on the shaft 126. Alockwasher 135 engaging the guide member 132 is mounted on the shaft 126in such a manner that it is prevented from moving from the right to theleft on the shaft 126 as viewed in FIG. 1. The outer periphery of theguide member 132 radially projects into an outwardly extending annularflange 136 which the tongue engages to retain the sleeve 124 inassembled relationship on the power element shaft 126. A helicalovertravel spring 138 encircles the shaft 126 and is mounted incompression between the guide 132 and a retainer 140 which is keyed toshaft 126 for movementtherewith. The attaching end of shaft 126 isintegrated; with an expansible power element 142 which may be of anysuitable type that is well known in the art. The power element 142 ismounted on the rear of casing 14 by means of a threaded stud 144 and alocknut 146. The stud 144 is provided with a central bore (not shown),one end of which communicates with the interior of the power element 142while its other end receives the end of a capillary tube 148 which inturn is connected to a temperature sensing bulb 150 suitably positionedin a space to be temperature controlled.

The power element 142, the stud 144, the capillary tube 148, and thesensing bulb 150 constitute a closed system filled with an expansiblefluid so that a variation of temperature sensed by the bulb 150 producesa corresponding expansion or contraction of the power element 142. Acorresponding movement of the power element shaft 126 is effective toproduce reciprocation of the valve member 116.

Adjacent the inner end of the gas cock 22, the front casing 12 isprovided with a pair of small bores (not shown), one of whichestablishes a bypass passage to the outlet 20, the other of whichestablishes a pilot passage to the pilot outlet connector 152. The flowsof fluid through these small bores are controlled by means of a pair offlow restrictors 154 (only one being shown) which separately intersectthe bypass passage and the pilot passage for individual adjustmentthereof. The pilot passage and the bypass passage are conventionalfeatures of the prior art and further description thereof is deemedunnecessary except to state that the pilot passage main-- tains a fiowof fluid to a pilot burner and the bypass passage maintains a minimumflow to fluid to a main burner whenever the gas cock 22 is in an openposition.

In order to place the thermostatic control device in operation, thecontrol dial 90 is depressed inwardly against the bias of coil spring 42whereby the lugs 48 and 50 are displaced axially from their slots 60 and62, respectively, in the cover 52. After the initial depression of thedial 90 releases the interlocking feature, the dial 90 is rotatedcounterclockwise to a desired temperature setting causing rotation ofthe gas cock 22 and the drive plate 106 which in turn rotates thethreaded valve seat 110 away from the valve member 116. Once the gascock I the bath; d'ui'ih this Q area 1 l Oh lisnsinsn, sneer renamesdrits or a combination thereof, dependihghipon' the particulartemperature setting, re'gisters'with" the inlet 19 the hpening betweenthe 'valve seat 1'10, and the ,valve member 116 permits the gas toflci'w't'o the outlet 20 toa main ignition at that location. H As thetemperature of the space beingheat'd hythe "main burnerapproachesthatforwhich the dial9'0 has been set, the thermally responsive meahsmoves the valve member 116 thwardthe valve seating' surface114. In orderto maintain the temperature of the space at 'a predetermined Setting,the "thermally responsive means effects reciprocation of the va lvem'emb'er 116-in a manner that is known in the art.

It IS app ar'eht ifrhm' the relative sizesand designs 6r load spr ihglfl'aiid'th'e o'ver'travel spring"I 33 ,as viewed in 'FIG. 1, that theovrtr'avelspr'ingISS exerts a greater force than that of the load spring122;"thus,

118 and the'valvemem'berdH mounted thereon as a unit with thetemperature responsive "means against the'bias of load s'pring122h'h'til the'vaivsmeman the flow offiuidto the'outlet 20. "In theevent an excessive tempei ature is'ser'isedby'the bhlb ISO'aftEr' thevalve firemen 116 'is' seated 'in' res onse to thermostatic action, theadditional "expans o of power element 142 causes compression of theover-never sprin 138 so as not to suhje'ct rheregmarin vawe 116 tonndiie' stress.

During such overtravel operation, the free"eh'd"ofpowr 'thevalve'seatllilwhe'reby the valve'seat'ingshrface'1I4 engages the regulatiiig valvemember 116 and simultaneously therewith the gas -c'ock 22is rotated toa' position where its tapered portion closes oft" the "inlet 19.

h jw rh theparticular'srrncturai arrangement of this thermostaticeontrol device, a" simplified cal'ibrati ii'g"operation permissiblewhichis aceomplished by placin thetemper'atur'e sens'ing'bulb 150 inab'at'h havinga prjed'eter- 'rnined temperature, forXample lOOT'FJtheerase is then retated countetclo ckwiejfintihthe valve seatingsurface-1141mm light'eohtactlwith themegulat'ing valve disc 116 Withthedial tl held annrysaasro'prev t "memes thereof and of 'ga's'cock 22, 'a'screwdriver "is ihserted throughhhe aperthre"99 of 'tlie' insert dap'fid and operably engages the set screw 194. The set screw 104 is thenloosened and thus releases the-rotational drive between the gas cock 22and the operating 'shaft 190. The dial 90 is then rotated eitherclockwise or counterclockhe; "tours 4009"Fftemperathre" "set- M 1F.temperatdreof atieii 'the' dial 9i sleeve 73, drive washer L 44anzr'gaficsek 'za'rorate unit relativeto the shaft 100, which had beenreleased from the gas cock 22 by the loosening of the set screw 104.Since the shaft 100 does not rotate, the movable valve seat 110 remainsin its contacting position relative to the regulating valve disc 116. Inorder to complete the calibrating operation, the dial 9% is held firmlyto prevent rotation of the dial 913, sleeve 78, drive washer 44, and gascock 22 while the set screw 104 is turned tight so as to effect therotational drive between the gas cock 22 and the operating shaft 100. Insome installations, it may be re quired that the insert cap 95 be asolid member with no central aperture; accordingly, the insert cap 98 isremoved for calibration purposes and then replaced after the calibrationis completed.

This thermostatic control device also includes a second calibrationfeature which is accomplished by 'placin'g the' billblSi) in'"a'bath of'a' predetemined temperature, such as 400 F., and then rotating dial 90to apositionwhe'r'e the valve seating surface 114 is in lightcontactjwith the regulating valve disc 116. When the surface 114*and thedisc 116 are in light contact, the temperature setting indicated bythe'dial '90 is compared with thef'400 F.

tempeiature of the bath and the difference is noted. This difference isthe value of the miscalibration which is to be adjusted. The dial90 isthen removed from the operating sleeve 78 and bezel 70 mayalsobefremovedi'if desired. It shouldbe noted that with bezel 70removed, theen'ti're reference mark 63 on the 'cover'52 is visiblebeasse it is located in the center of the'split of'collar 68.

However, bezel removal'is not necessary because when in its proper postion, theoute'r'portion of reference mark 63 is visible including theendof mark63whi'ch is disjposed on the outer edge'of thecover cylindricalportion 64. 7

Continuing with the calibrating operation, the operating "sleeve 78 'isheld firmly so as not-to rotate and a screwfdriver'engag'es the setscrew 104 to loosen the same. Loosening of the set screw 104 disengagesthe rotational drive between the gas cock 22 and the operating shaft100. The sleeve 78 is then rotated either clockwise or counterclockwise,as the case may be,an angular distance corre- "spendin to the notednumber of degrees of miscaliblration. For instance,if -each"graduation86 is desi'gned to represent a 10 F. temperaturevariation'and the noted miscalibrat ion is also a 10 F. temperaturedifference, the's'leeve "i8 is rotatedan angular distanceof onegraduation'86 relativeto the fixed referencemark63" on the cover '52.During such rotation, the sleeve '78, drive washer 44, and gas cock 22'rotate as a unit relative to the shaft 1 00,wl1ich had been releasedfrom the gas cock 22by the loosening of the set screw 1G4. Since theshaft 1% does not rotate, the movable valve seat 11% remains in itscontacting position relative to the regulating valve disc 116.In'coinpleting the calibration operationfthe sleeve 78 isheld firmly toprevent rotation' of-the sleeve '78,'-drive washer 44, and gas cock22while the setscrew 104 is then tightened, the dial 90 is replaced andthe calibration is completed. H K

FIGSUS and '6 show a modifieation ef the-"ope'ratiiig sleeve for use'with a D shaped socketed control dial. As

is illustrated in FI Gi S, theoperatingsleeve178 is ge'nerallycup-shaped, having a cyl'indrical onisnasde eentral aperture initsbottom wall. The sleeve 178- is piovided with a longitudinallyextendinginwardly" bent-t'aihg 1 intermediately 'spaced in angularrelationshipbetween a pair of r ectangulardetents'182 (only one beingshown). B'etween-"the end of" sleeve 17'8"a'1id the edge of each rec-'tangular detent 182,:the sleeve 178 isfdehted-inwardly to form a keeper184. V Calibratingfindiciafin'the foi m' ofa plurality of longitudinallyeXtendin'g-graduations' 186 "are radiallyspaced about the outer surfaceof the cylindrial portion-of sleeve178,'which'graduations terminate inradially extending graduations 187 formed jon thebots tem 188,'having 1aD-shaped cross sec'tion, is'provided with an axialpassageway 1'89whichis 'c'oncentricwith the opening in the bottom wall of thecup-shaped sleeve member 178. One end. of the D-shaped stem 188 issecurely fastened to the bottom wall of the cup-shaped sleeve member 178while its opposite end receives a conventional control dial having aD-shaped socket.

As is illustrated in FIG. 6, the indicia end marks 187 cooperate withthe end of reference mark 63 on the edge Inasmuch as the abovedescription and the drawings are subject to various changes instructural details and reversals of parts, it is intended that theforegoing description and drawings be interpreted as illustrative andnot in a limiting sense.

I claim:

1. In a control device, the combination comprising a housing having anopening, an inlet and an outlet, first valve means in said housingmovable between a plurality of positions for controlling a flow of fluidinto said housing and including a bored stem portion extending throughsaid opening, second valve means in said housing movable between aplurality of positions for regulating a flow of fluid out of saidhousing, an apertured member surrounding said bored stem portion andsecured to said housing adjacent said opening, a sleeve member extendinginto said apertured member and being operatively connected to said boredstem portion for moving said first valve means, an element carried bysaid first valve means having one part terminating within said boredstem portion and another part operatively connected to said second valvemeans, locking screw means concentrically carried by the bored stemportion of said first valve means and abutting said one part of saidelement and locking said element to said first valve means for unitarymoveoutlet, control valve means movably disposed adjacent said inlet forcontrolling a fluid flow into said housing and having a bored stemportion extending through said opening, a sleeve member operativelyconnected to said bored stem portion for moving said control valvemeans, regulating valve means movably disposed in said housing forregulating a fluid flow out of said housing, thermally responsive meansincluding a power element operatively connected to said regulating valvemeans for moving the same in response to temperature variations, a coverelement secured to said housing adjacent its opening, a shaft membercarried by said control valve means having one end terminating withinsaid bored stem portion and being operatively connected to saidregulating valve means, locking screw means carried by said controlvalve means and being operatively disposed within said bored stemportion, said locking screw means being operative to lock said shaftmember to said bored stern portion for simultaneously positioning saidcontrol valve means and said regulating valve means and operative torelease said shaft member from said bored stem portion permittingcalibrating adjustment of said control valve means independently of saidregulating valve means, and cooperating indicia on said sleeve and saidcover to facilitate calibration when said locking means is released andsaid control valve means is movable relative to said shaft member.

3. In a thermostatic control device, the combination comprising ahousing having an opening, an inlet and an outlet, a valve chamber insaid housing disposed between said inlet and outlet, a movable valveseat disposed in said chamber, a valve member cooperating with said seatand being movable relative thereto to regulate a flow of fluid to saidoutlet, thermally responsive means including a power element operativelyconnected to said valve member for moving the same in response totemperature variations, a fixed valve seat in said housing adjacent saidinlet, a hollow valve member rotatably disposed in said fixed valve seatand having port means adapted to register with said inlet, said hollowvalve member including a bored stem extending through the opening insaid housing, an abutment shoulder in said bored stem, an aperturedcover for said stem secured to said housing, an operating shaft havingone end terminating within said bored stem and having an opposite endoperatively connected to said movable valve seat, an abutting surface onthe one end of said operating shaft and cooperating with said abutmentshoulder, locking screw means threadedly disposed in said bored sternand abuttingly engaging the one end of said operating shaft for lockingsaid abutting surface to said abutment shoulder to effect simultaneousmovement of said movable valve seat and said hollow valve member, asleeve member extending into said apertured cover and being operativelyconnected to said stem for rotating said hollow valve member, firstindicia means on said apertured cover, and second indicia means on saidsleeve member and cooperating with said first indicia means to indicatean adjustment value for calibration purposes.

4. The combination as recited in claim 3 wherein said sleeve membercomprises a hollow cylinder and said second indicia means are formed bylongitudinal graduations on a portion of said cylinder, and a controlknob is mounted on said cylinder for manual operation to effectselective positioning of said movable sleeve member.

5. The combination as recited in claim 3 wherein said sleeve membercomprises a cup-shaped element having a cylindrical portion and anapertured bottom wall, a longitudinally bored shaft element secured tosaid bottom wall, and said second indicia means are formed bygraduations extending longitudinally on the cylindrical portion andradially on the bottom wall, and a control knob is mounted on saidlongitudinally bored shaft element for manual operation to effectselective positioning of said movable sleeve member.

6. The combination as recited in claim 3 wherein a control dial ismounted on said sleeve element for manual operation to effect selectivepositioning of said movable valve seat, and said control dial isprovided with aperture means defining tool insertion means whereby saidlocking means is releasable for calibration purposes with said controldial remaining mounted on said sleeve element.

References Cited in the file of this patent UNITED STATES PATENTS2,153,886 Grayson Apr. 11, 1933 2,303,011 Weber et a1 Nov. 24, 19422,746,686 Loveland May 22, 1956 2,807,432 Eskin Sept. 24, 1957

